Rotary expansion engine of the wankel type

ABSTRACT

A multi-unit rotary expansion engine of the Wankel type capable of operating with pressurized gaseous or vaporous fluid. Each unit has a rotor housing within which a multi-lobed rotor rotates with and about an eccentric or crank portion of a crankshaft drivably connected to the rotor, the rotor and housing defining therebetween a plurality of working chambers which successively expand and contract in volumetric size as the rotor rotates relative to the housing. Each unit includes a plurality of spaced inlet ports and exhaust ports communicating with the working chambers to admit pressurized fluid into the latter and pass exhausted pressurized fluid from the working chambers. Valve means is provided for each of said inlet ports for controlling admission of pressurized fluid into the working chambers for a period of more than 90* of rotation of the crankshaft. The rotors of the multi-unit expansion engine are angularly offset relative to each other 180* so that with the timing of operation of the intake valves at least one inlet port is open to its associated working chamber and instant starting of the mechanism upon application of pressurized fluid to the inlet ports is achieved.

United States Patent 91 Pierce et a1.

1 1 ROTARY EXPANSION ENGINE OF THE WANKEL TYPE [75] Inventors: Erold F. Pierce, Lakewood; Richard M. Gigon, Westfield; Walter L. Hermes, Cedar Grove, all of NJ.

[73] Assignee: Curtiss-Wright Corporation,

Wood-Ridge, NJ.

22 Filed: Dec. 16,1971

211 Appl. No.: 208,692

[521 US. Cl 418/60, 418/61, 418/83 [51} Int. Cl........ FOlc 1102, F04c U02, F040 17/02 [58] Field of Search 418/60, 61, 83, 212,

[56] References Cited UNITED STATES PATENTS 1,655,738 1/1928 Rasck 418/212 3,535,059 10/1970 Kalkbrenner 418/60 3,628,899 12/1971 George 418/61 3,519,373 7/1970 Yamamoto 418/61 3,289,647 12/1966 Turner et a1... 418/60 1,481,865 1/1924 Haeseler 418/60 1,968,537 7/1934 Plato 418/212 3,208,666 9/1965 Fezer et a1. 418/60 3,352,290 11/1967 Kuroda 418/60 Primary Examiner-Carlton R. Croyle July 10, 1973 Assistant Examiner-John .1. Vrablik Att0mey-Arthur Frederick et al.

[ 5 7 ABSTRACT A multi-unit rotary expansion engine of the Wankel type capable of operating with pressurized gaseous or vaporous fluid. Each unit has a rotor housing within which a multi-lobed rotor rotates with and about an ec centric or crank portion of a crankshaft drivably connected to the rotor, the rotor and housing defining therebetween a plurality of working chambers which successively expand and contract in volumetric size as the rotor rotates relative to the housing. Each unit includes a plurality of spaced inlet ports and exhaust ports communicating with the working chambers to admit pressurized fluid into the latter and pass exhausted pressurized fluid from the working chambers. Valve means is provided for each of said inlet ports for controlling admission of pressurized fluid into the working chambers for a period of more than 90 of rotation of the crankshaft. The rotors of the multi-unit expansion engine are angularly offset relative to each other 180 so that with the timing of operation of the intake valves at least one inlet port is open to its associated working chamber and instant starting of the mechanism upon application of pressurized fluid to the inlet ports is achieved.

11 Claims, 12 Drawing Figures Patented July 10, 1973 8 Sheets-Sheet 1 Patentd July 10, 1973 8 Sheets-Sheet 2 INVENTORS /7 1 /5965 Patented July 10, 1973 3,744,940

8 Sheets-Sheet 3 IN VENTORS 7 0.40 P awn: lp/osw/ arf. 6/60/1/ BY Marx/( 4. fif/P/ffs Patented July 10, 1973 8 Sheets-Sheet 4 INVENTOR5 Patented July 10, 1973 I 8 Sheets-Sheet 5 III/III WAY/"Z7? 4 55/ /7415 Patented July 10, 1973 8 Sheets-Sheet 7 Patented July 10, 1973 3,744,940

8 Sheets-Sheet a ROTARY EXPANSION ENGINE OF THE WANKEL TYPE This invention relates to rotary expansion engines or mechanisms capable of operating with pressurized gaseous or vaporous fluids and, more particularly, to rotary expansion engines having a multi-lobed rotor eccentrically mounted for rotation in a housing, such as disclosed in U. S. Pat. No. 2,988,065.

BACKGROUND OF THE INVENTION For certain applications, as where noise and vibration are to be kept to a minimum, it may be desirable to provide motive power by the generation of pressurized fluid outside of the working chambers of a prime mover. One such application is for the propulsion of a torpedo where the pressurized fluid may be generated in a reactor by the chemical reaction of a mixture of hydrogen peroxide, diesel fuel and sea water, which pressurized fluid is then passed to and through a power plant for driving a propeller. For torpedo propulsion, a turbine power plant is usually employed, but has the disadvantage of requiring high RPM before attaining a desired output torque. The rotary expansion engine of the present invention, being a positive displacement mechanism, overcomes the aforesaid disadvantage and, also being light in weight and relatively small in size, is particularly useful for the power plant of a torpedo.

While the expansion mechanism of this invention may be used as a prime mover for a torpedo, its usefulness is not limited to such application. The mechanism has application equally as well as any vehicle requiring an external combustion cycle wherein reduced pollution is desired. Also, the expansion mechanism according to the invention, may be used with a wide range of pressurized fluids, such as steam, compressed air, combustion products of various fuels, resultant gases of various chemical reactions, and the like.

Two of the problems connected with the utilization of the rotary mechanisms of the types disclosed in the U.S. Pat. No. 2,988,065 to Wankel et al. and the British Patent No. 583,035 to Bernard Maillard, as a gas expander, are the means of starting the mechanism and the generation of a continuous output torque without reversals. Obviously, the use of a self-starter device in some uses, such as required in the gas expansion engine disclosed in U.S. Pat. No. 2,680,430, is not desirable for reasons of space and weight limitations, particularly as a propulsion means for a torpedo. It is equally clear that output rotation must be in a selected direction for the mechanism to have utility.

Accordingly, one of the objects of the present invention is to provide a rotary expansion engine capable of continuous ouput torque without reversal of rotation.

Another object of this invention is to provide a rotary expansion engine which is capable of instant starting without the need of a self-starting device.

A further object of the present invention is to provide a rotary expansion engine which is of compact, relatively simple construction and is light in weight relative to its brake horsepower output.

A feature of this invention is the employment of at least two rotor-housing units arranged with the rotors angularly offset or indexed 180 relative to each other and the housings of the units angularly offset or indexed 90 from each other. Also, each rotor-housing unit is drivably connected to the crankshaft so that for each rotor revolution the crankshaft rotates three times. Two pairs of intake and exhaust ports are arranged in each rotor-housing unit so that two power impulses per crankshaft revolution or six per rotor revolution are produced. This means for two rotors there will be four power impulses per cranksahft revolution or 12 for each revolution of the two rotors. A valve means is provided for each of the intake ports for controlling admission of pressurized fluid into the working chambers for a period of at least and preferably to about of crankshaft rotation. These structural features coact to provide a rotary expansion mechanism capable of producing a continuous output torque in a preselected direction and wherein at least one intake port is open to its associated working chamber to thereby achieve instant starting of the mechanism upon application of pressurized fluid to the intake ports.

Another feature of the invention is the gear train timing of the operation of the intake valve means relative to the rotation of the crankshaft.

A still further feature of the present invention is the integration of the valve timing gear train with the reduction gear drive train.

SUMMARY OF THE INVENTION The rotary expansion engine capable of operating with pressurized gaseous or vaporous fluid contemplated by the present invention comprises at least two tandemly arranged rotor-housing units and a single crankshaft connected to drive a member, such as a propeller. In general, the structure is similar to the tworotor housing, internal combustion engine disclosed in the patent to Sollinger, U.S. Pat. No. 3,096,746.

Each rotor-housing unit comprises a rotor housing having a cavity within which a multi-lobe rotor rotates with and about an eccentric portion of the crankshaft to drive the latter. The rotor and associated housing are so contructed that they define within the housing cavity a pluraltiy of working chambers which successively increase and decrease in volumetric size as the rotor rotates relative to the housing. The rotor may be of general triangular configuration with three lobes or apex portions while the peripheral surface of the housing cavity may have an epitrochoidal shape so that the rotor and housing define three working chambers. Each rotor-housing unit includes a plurality of spaced inlet or intake ports and outlet or exhaust ports communicating with the working chambers to admit pressurized fluid into the latter and pass exhausted pressurized fluid from the working chambers. In a three working chamber rotor-housing unit, it is contemplated that the engine is to be provided with two pairs of intake and exhaust ports so that there are two power impulses for every revolution of the crankshaft or six power impulses per rotor revolution in an engine having 3:1 drive ratio between the crankshaft and rotor. To properly time the introduction of pressurized fluid, through each intake port, into the working chambers, a valve means is provided for each intake port for controlling admission of pressurized fluid into the working chambers for a period of at least 90 of rotation of the crankshaft and preferably, in the engine herein described in disclosing the invention, the intake valve means is open for about [40 of rotation of the crankshaft. The dual exhaust ports are located in the housing end walls and flow therethrough is controlled by action of the rotor. Preferably, each exhaust port is located relative to top dead center to begin to open at about 270 and close at about 495 of crankshaft rotation.

Each of the inlet ports is in communication with a source of pressurized fluid, such as a combustion chamber, reactor, compressor, or the like, through an inlet manifold. Similarly, each of the exhaust ports communicate with a discharge manifold which receives and passes the spent pressurized fluid to a point of discharge.

The rotors of the rotor-housing units are arranged in a 180 offset or indexed relationship to each other, while the housings of the units are angularly offset or indexed 90 from each other. This relationship of the rotor-housing units and the timing of the valve means for the intake ports provides the rotary expansion engine with a continuous output torque in a preselected direction and provides that at least one intake port is open to a working chamber in all positions of the crankshaft so that the engine can be instantaneously started upon application of pressurized fluid to the intake ports.

The proper sequential operation of each of the valve means in relation to the crankshaft angular position is achieved by interconnecting the several valve means with the crankshaft through a gear train or other positive drive such as chain or belt, which may also include means for varying inlet valve timing if a wider range of power demand is to be satisfied.

In another aspect of this invention the valve timing gear train is integrated in a reduction gear drive assembly.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following detailed description thereof when considered in connection with the accompanying drawings wherein two embodiments of the invention are illustrated by way of example, and in which:

FIG. 1 is an end elevational view of the rotary expansion engine according to this invention;

FIG. 2 is a longitudinal cross-sectional view taken substantially along lines 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a view in cross-section taken along line 4-4 of FIG. 2 showing the combined reduction drive gear and intake valve timing assembly;

FIG. 5 is a transverse sectional view taken along line 5-5 of FIG. 2 showing one of the rotor housing units and the intake manifold;

FIG. 6 is a cross-sectional view, similar to FIG. 5, taken along line 6-6 of FIG. 2 and showing the other rotor housing unit and the intake manifold;

FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 3 showing the exhaust manifold;

FIG. 8 is a fragmentary view in cross-section of an alternative intake valve;

FIG. 9 is a graph illustrating the intake valve operation in relation to crankshaft position and output torque cycle; and

FIGS. 10, 11 and 12 are schematic illustrations of the rotary expansion engine showing various positions of the rotors relative to the angular position of the crankshaft.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Now referring to the drawings and more particularly, FIGS. 1 to 7, the reference number 10 generally designates the rotary expansion engine according to this invention which, while shown and described as useful as a powerplant for a torpedo, is not limited to such application. The expansion engine 10 has a broad range of usefulness and particular utility where relatively quiet, vibrationless, high torque, motive power is desired.

The expansion engine 10 as best shown in FIGS. 1 and 2, comprises two rotor-housing units 12 and 14 which are arranged in tandem and having a common crankshaft 16. Each of the rotor-housing units 12 and 14 have multi-lobe rotors l8 and 20, respectively. The housing for rotor-housing unit 12 comprises an end wall 22, an intermediate wall 24 and peripheral wall 26, while rotor-housing unit 14 consists of an end wall 28, intermediate wall 24 and a peripheral wall 30. The end walls 22 and 28, intermediate wall 24 and peripheral walls 26 and 30 are secured together by circumferentially spaced tie-bolts 32 (see FIGS. 1, 3 and 7). Each of the peripheral walls 26 and 30, as best illustrated in FIGS. 5 and 6, may be formed to have an internal peripheral surface of epitrochoidal configuration. The rotors l8 and 20 may be constructed, as shown, so as to have a generally triangular shape with three lobe or apex portions 34. The rotors are supported eccentrically on crank portions 36 and 38 of crankshaft 16 which is supported for rotation in bearing 40 and 42 located in housing end walls 22 and 28. Each of the rotors carries a gear 44 which meshes with and is eccentrically located relative to fixed gears 46 secured to end walls 22 and 28, the gears having a ratio value, such as 3 :2 to thereby effect three revolutions of the crankshaft for every revolution of rotors 18 and 20. As best shown in FIGS. 5, 6, l0, l1 and 12, rotor 18 and the housing of rotor-housing unit 12 define three working chambers A, B and C, while rotor 20 and the housing of rotorhousing unit 14 define three working chambers A, B and C. The working chambers A, B, C and A, B and C successively change in volumetric size as the rotors rotate within and relative to their associated housings.

Since the engine of this invention operates from an external source of pressurized fluid and not as a result of combustion within the working chambers, a compression stroke is unnecessary and, therefore, two power impulses or strokes per revolution of the crankshaft, for each rotor is provided. To this end each of the rotor-housing units 12 and 14 has two pairs of intake and exhaust ports. The rotor-housing unit 12 has, as best shown in FIGS. 2, 5, 6 and 7, two spaced intake ports 48 and 50 located in peripheral wall 26 of rotorhousing unit 12, while two spaced intake ports 52 and 54 are provided in peripheral wall '30 of rotorhousing unit 14. The rotor-housing unit 12 is also provided with two exhaust ports 56 and 58 in end wall 26, while rotorhousing unit 14 has two exhaust ports 60 and 62 which are located in end wall 28 (see FIGS. 3,5 and 6). The intake ports 48 and 50 of rotor-housing unit 12 and intake ports 52 and 54 of rotor-housing unit 14 in communication with a pressurized fluid supply conduit 64 (see FIG. 2) through a ring-shaped intake manifold assembly 66 and feed line elbows 68. As best shown in FIGS. 3 and 7, exhaust manifold passageways 70 and 72 are formed as integral portions of end walls 22 and 28, respectively, to communicate with and receive spend pressurized fluid from the exhaust ports. The exhaust manifold passageway 70 communicates with exhaust ports 60 and 62 in end wall 28 while exhaust manifold passageway 72 is in communication with exhaust ports 56 and 58 in end wall 22. As best shown in FIG. 3, exhaust manifolds 70 and 72 connect with secondary exhaust pipe assemblies 743 and "/6, respectively, which assemblies, in turn, are connected to communicate with a main exhaust passageway 78 formed by a hollow drive shaft 80.

As is best shown in FlGS. 5., 6 and 9, to provide for smooth, continuous output torque the rotors l8 and 20 are angularly indexed or offset 180 from each other, while epitrochoidal-shaped cavity of the rotor-housing units are angularly offset or indexed 90 from each other. Also, coordinated flow of pressurized fluid through each of the intake ports 48, 50, 52 and S4 is required to provide for four equally spaced power imrotors 18 and 20 to thus produce a smooth, continuous output torque. As can be understood by reference to the graph of FIG. 9 wherein torque of each of the rotors is plotted against the angularity of the crankshaft, the power impulses of each of the rotors are 90 out of phase so that a power impulse or output torque is occurring in one rotor-housing unit while the other rotorhousing unit is exhausting the spent pressurized fluid. In other words, since each rotor-housing unit 12 and 14 provides two power impulses or strokes for each revolotion of the crankshaft or six power impulses per revolution of each of the rotors, one rotor-housing unit is always under the influence of expanding pressurized fluid supplied to one of its working chambers A, B, C or A, B, C through the intake ports 48, 50, S2 and 54.

To provide coordinated flow of pressurized fluid into the working chambers through intake ports 48, 50, 52 and 54 and provide expansion engine with selfstarting characteristics in a preselected direction of rotation upon application of pressurized fluid to the intake ports, a rotary valve 82 is disposed adjacent each of the intake ports, which rotary valves 82 are coordinated and timed in operation relative to crankshaft rotation by a combined reduction drive gear and intake valve timing assembly 84 (see FIGS. 2 and 4).

Each rotary valve 82 comprises a cylindrical head portion 85 and an axially extending stem portion 86 disposed in the housing with the head portion 85 rotatably mounted in a bearing sleeve 88 secured in a pcripheral wall 26 or 30 adjacent its associated intake port. Each of the intake ports 48, 50, 52 and 54 comprise aligned holes in the associated peripheral wall. The head portion 85 of valve 82 has a diametrical hole 90 which rotates with the head into and out of registry with aligned holes constituting the adjacent intake port. Each valve 82 is rotated by a gear 92 which is secured to valve stem 86 by a spline connection at 94. Each of the four gears 92 form part of the reduction drive gear and intake valve timing assembly 84. In view of the fact that rotary valves 82 and bearing sleeves 38 are subjected to very high temperatures they are constructed of heat resistant materials, such as stainless steel and graphite, respectively.

As best shown in FIGS. 2 and 4, reduction drive gear and intake valve timing assembly 84 comprises, in addition to gears 92, a drive gear as which is spline connected to crankshaft l6 and in meshing relationship to pulses per crankshaft revolution or 12 per revolution of each of the gears 92. The transmission of rotation from gear 96 to gears 92 effects rotation of each of the valves 82 and coordinates the rotation of the valves relative to each other and the crankshaft. To provide for the transmission of crankshaft rotation to drive shaft 80, each of the gears 92 has an elongated hub portion 98 which extends in spaced parallel relationship to the axes of crankshaft l6 and drive shaft (see HQ. 2). The ends of elongated hub portions 98 or jackshafts are journalled in bearings supported in a spider 100. A gear 102 is connected adjacent the distal end of each of the elongated hub portions 98 for conjoined rotation with the latter and in mesh with a gear R0 5 which is connected to drive shaft 80, the drive shaft 80 being supported for rotation in the hub portion of the spider assembly i100. Fluid seals 1106 are also mounted in the hub portion of spider assembly 100 to seal the interstices between the outer peripheral surface of drive shaft 80 and the spider assembly so that exhaust fluid does not by-pass exhaust passageway 78 in drive shaft 80 and lubricant is retained at the drive shaft bearings.

A two-step speed reduction between crankshaft l6 and drive shaft 80 is achieved by making gear 96 of smaller pitch diameter than each of the gears 92, the gear ratio between gears 102 and gear ill-t being about 2.211 while the ratio between gears 96 and 92 is about 2:1. The ratios of gears 96, 92 and gears 1102 and 1104 may provide an overall reduction of crankshaft speed from about 7,000 RPM to a drive shaft speed of about 1,600 RPM.

As illustrated in the graph of FIG. 9, the intake rotary valves 82 of intake ports 38, 50, 52 and 54 are coordinated and timed to begin to open and close during a period of crankshaft rotation of more than 90 and, as shown, preferably for about of crankshaft rotation. This period in which each rotary valve 82 is open is adjusted relative to each other and crankshaft rotation so that one of the valves is open to communicate a working chamber with the intake manifold 66 at all angular positions of the crankshaft. Thus, whenever the expander engine 110 is to be driven by admittance of pressurized fluid into intake manifold assembly as and regardless of the position of the crankshaft, pressurized fluid passes through the open valve into a working chamber thereby impressing a torque force on the rotor and starting the engine to rotate in the preselected direction. The rotary valves 82 are essential to insure rotation upon starting in the desired preselected direction, since pressurized fluid will be passed only into a working chamber that has the rotor in the proper position (TDC or beyond) to avoid the application of negative torque on the rotor.

The flow of spent pressurized fluid through exhaust ports 56, 58 and 60, 62 is controlled by rotation of rotors 18 and 20, respectively. Of course, exhaust ports 56, 58, 60 and 62 are positioned such that each does not begin to open until about 270 of crankshaft rotation (about 90 of rotor rotation) from top dead center" (TDC) of each power impulse and closes at about 495 of the crankshaft rotation or of rotor rotation.

As best illustrated in l lGS. llll, llll and 112, the sequence of operation of expansion engine 110 in relation to crankshaft rotation is as follows:

As shown in MG. 110, when rotor R8 is in the top dead center" (TDC) relative to intake port 38, and at 0 of crankshaft rotation, intake valve 82 of intake port 48 begins to open to admit pressurized fluid into working chamber A, the fluid exerting a torque force on rotor 18 causing the latter to rotate in a clockwise direction. At this time, by reason of the 180 offset relationship of rotor 20 to rotor 18 and the 90 angular offset of the housings, rotor 20 of rotor housing unit 14 is at about a midintake point relative to intake port 52. As rotor 12 rotates, valve 82 of intake port 48 continues to open and then starts to rotate to a closed position simultaneously with the expansion of pressurized fluid in chamber A. The intake valve of intake port 48 is fully closed after about 140 of rotation of crankskshaft 16 or about 47 of rotor rotation (FIG. 11). At this time rotor 20 is approaching TDC with respect to intake port 54. The pressurized fluid continues to expand in chamber A forcing rotor 18 to rotate until exhaust port 56 begins to be exposed at about 270 of crankshaft rotation or BDC to communicate working chamber A to exhaust manifold 70. With rotor 18 in this BDC position, rotor 20 is under the torque force of expanding pressurized fluid admitted into working chamber B through intake port 54 (see FIG. 11). As the rotor continues to rotate, exhaust port 56 remains open for about 225 of crankshaft rotation or 75 of rotation of rotor 18. At 540 of crankshaft rotation, rotor 18 next moves into a TDC position (not shown) relative to intake port 50 and intake valve 82 associated with intake port 50 opens to admit another charge of pressurized fluid into chamber A so that the second power impulse is imparted to the rotor in its 360 of rotation. Thereafter, the sequence of operation relative to the closing of intake port 50 and the opening and closing of exhaust port 58 is the same as previously described with respect to intake port 48 and exhaust port 56.

The sequence of operation of rotor 20 is the same as that of rotor 18, except that as previously stated it is 90 out of phase with rotor 18.

To better understand the significance of crankshaft rotation in excess of 360, it must be borne in mind that the expansion engine, herein described and shown, is one in which the crankshaft is rotated three revolutions for every single revolution of the rotor. With a 3:1 ratio the crankshaft rotates through a total of l080 (360 X 3) for every 360 of rotor rotation. During such crankshaft rotation (1080) each of the three peripheral edges of each rotor is subjected to two power impulses or a total of six power impulses per rotor per revolution. This means that for each rotor there is a power impulse for every 180 of rotation of crankshaft 16 (1080 divided by 6); therefore permitting, as shown in FIG. 9, the arrangement of the power impulses of rotors l8 and 20 90 out of phase.

In the expansion engine thus far described, control means (not shown) such as a valve, must be provided to control flow of pressurized fluid into the intake manifold and/or-some other regulation means for controlling the generation of pressurized fluid in a combustion or reaction zone 110 (only a portion of which is shown in FIG. 2).

The expansion engine may be housed within a shell 112, such as a casing of a torpedo. To support the engine within shell 112, the housing end walls 22 and 28 are provided with radially extending flange portions 1 14 which engage the interior surface of shell 112. The

spider assembly 100 also abuts the inner surface of shell 112 to support drive shaft and support part of reduction drive gear and intake timing assembly 84.

The expansion engine 10 may be suitably cooled by means of air as disclosed in U.S. Pat. No. 3,196,850 to Jones or, as shown, by the circulation of cooling liquid through fluid flow channels 115 in the engine housing (see FIGS. 2, 5 and 6). Since the housing units 12 and 14 are angularly offset from each other and the intake ports 48, 50, 52 and 54 are arranged in 90 angular spaced relationship, a substantially uniform heating of the housing is achieved so that effective cooling can be provided by a once through coolant flow path as distinguished from the reverse, multi-flow coolant flow path system disclosed in the U.S. Pat. to Turner et al. No. 3,289,647. Accordingly, channels may be formed to extend substantially parallel to the axis of crankshaft l6 and connected through a header (not shown) to a source of coolant to provide for a single pass flow of coolant through the rotor-housing units. As best shown in FIG. 2, rotary intake valves 82 which may be exposed to pressurized fluid temperatures of l,O00F or more are cooled by cooling fluid flow adjacent the intake valves 82 as such cooling fluid flows through channels 115. Further engine cooling is achieved by flow of lubricant through the engine parts, including the interior of rotors l8 and 20. An oil heat exchanger (not shown) is provided in the lubrication circulation system to cool the heated oil before tis recirculation through the system. Likewise, a cooling fluid heat exchanger may be employed to cool the heated cooling liquid before recirculation through channels 115. In the alternative, if there is a constant source of cooling fluid, such as sea water, where the engine is used to propel a torpedo, the heat exchanger can be omitted and the cooling system can be of the oncethrough type.

In FIG. 8 is shown an alternate rotary intake valve 116, which may be substituted for rotary intake valve 82 shown in FIGS. 2, 5 and 6. Rotary intake valve 116 has a barrel or hollow cylindrical valve body 1 18 which is journalled in a bearing sleeve 112 and is open at one end. The bearing sleeve 112 has a helical groove in the outer surface thereof which defines with the surface of a bore 120 in the rotor housing a helical passageway 122. The passageway 122 communicates, at one end, with the channels 1 15 so that cooling fluid is conducted by the passageway 122 around rotary intake valve 116 to cool the latter. The intake valve 1 16 has a radial hole 124 in the valve body, similar to hole 90 of rotary intake valve 82, which in a fully open position is in alignment with the aligned holes forming its associated intake port, e.g., 48, to communicate the associated working chamber with the intake manifold. The pressurized fluid flows, when hole 124 communicates the adjacent port with the interior of valve body 1 18, from the intake manifold 66 through the interior of the valve body and thence through hole 124 and the intake port. The rotation of each of the intake valves 116 is timed through its drive gear 126 relative to crankshaft rotation in a 1:1 ratio to achieve valve actuation in the same manner as previously described with respect to intake valves 82.

While the present invention has been shown and described as comprising two rotors, it is within the purview of the present invention to construct the expansion engine of more than two rotors; the valve timing and angular offsetting of the rotors are adjusted to provide the controlled admission of pressurized fluid for self-starting characteristics and smooth, uniform output torque as herein described. Also, while the present invention is shown and described as having a three-lobe rotor rotating within a two-lobe epitrochoidal housing, it is not limited to such construction. it is within the scope and spirit of the present invention to construct expansion engine 10 of any ratio of rotor lobe configuration to housing lobe shape. For exa'mpie, the engine may comprise a two-lobed rotor running in a threelobed housing or a four-lobed rotor running in threelobed housing. In addition, without deparature from the scope and spirit of the invention, the expansion engine of this invention may have a stationary or fixed rotor and a rotatable housing.

In view of the foregoing, it is believed readily apparent that the present invention provides a rotary expansion engine of the Wankel type which is capable of instant starts without regard to the angular position of the crankshaft and without the need for an external starting mechanism. It is a rotary expansion engine which provides smooth, high output torque at low RPM and can cover a broad range of speeds.

Although only one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the arrangement of parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

i. In a rotary expansion engine capable of operating on a source of pressurized fluid externally located with respect to the engine, the combination comprising:

a. a housing consisting of plural housing sections each of which define a cavity, the peripheral surface of which are so formed as to define a plurality of lobes;

b. a crankshaft supported for rotation in said housing;

c. a multi-lobe rotor supported for eccentric rotation in each of said cavities and connected to rotate said crankshaft;

d. each multi-iobe rotor having one more lobe than the number of housing lobes to define with its associated cavity a plurality of working chambers which successively expand and contract in volumetric size as the rotor rotates within its cavity;

e. a source of pressurized fluid external of the housing of the rotary expansion engine;

f. a plurality of intake and exhaust ports for each cavity circumferentially spaced from each other to provide a plurality of power impulses for every revolution of the associated rotor;

g. the housing sections being angularly offset from each other and the rotors also being angularly offset from each other around the crankshaft so that the rotors and crankshaft are substantially dynamically balanced and the intake and exhaust ports of all the cavities are substantially angularly equispaced from each other around the crankshaft to effect thereby substantially equal spaced power impulses for every revolution of the rotors;

. each intake port being in communication with said source of pressurized fluid to receive and pass pressurized fluid into the working chambers;

till

i. first valve means at each intake port to control flow of pressurized fluid therethrough;

j. second valve means for controlling flow of spent pressurized fluid from each of the working chambers through the exhaust ports; and

k. actuating means for moving said first valve means, in relation to rotation of the rotors in each of the cavities to open and closed positions.

2. The apparatus of claim ll wherein said actuating means is a gear train interconnecting each of the first valve means in synchronized relationship so that regardless of the position of the rotors at least one first valve means is open to admit pressurized fluid from said source thereof to effect rotation of the rotors in a preselected direction.

3. The apparatus of claim 31 wherein there are two rotors disposed in two cavities and wherein each rotor is operatively connected to rotate one revolution for every three revolutions of the crankshaft.

4. The apparatus of claim 11 wherein the engine has two rotors positionally indexed around the crankshaft from each other 180 and the housing sections positionally indexed about the crankshaft from each other.

5. The apparatus of claim 1 wherein the engine has two housing sections each of which defines a cavity having an epitrochoidal peripheral surface and wherein each rotor comprises a three lobe profile, the two rotors being positionally indexed about the longitudinal axis of the crankshaft from each other and the housing sections together with their epitrochoidal peripheral surfaces being angularly offset 90 from each other about the longitudinal axis of the crankshaft.

6. The apparatus of claim 1, wherein said source of pressurized fluid includes an intake manifold connected to communicate with each of said intake ports.

7. The apparatus of claim 1 wherein each of said first valve means comprises a valve body disposed for rotation in a valve housing and wherein said valve housing has fluid flow passageway means for conducting cooling fluid.

8. The apparatus of claim 1 wherein said housing has cooling fluid channels extending substantially parallel to the crankshaft axis and connected at one end to a source of cooling fuid to provide for a single pass of cooling fluid through the channels.

9. The apparatus of claim ll wherein each cavity has a basically epitrochoidal shape and each rotor has a three-lobe profile and wherein each cavity has a pair of intake and exhaust ports arranged to provide two power inpulses for each revolution of the crankshaft.

10. The apparatus of claim 9 wherein said actuating means provides for opening a first valve means for every 180 of crankshaft rotation to permit flow of pressurized fluid through the associated intake port and into a working chamber.

11. The apparatus of claim 9 wherein said actuating means provides for each power impulse the opening and closing of the associated first valve means within the period between about 90 to about [40 of crankshaft rotation and each exhaust port to open at about 270 of crankshaft rotation and close at about 495 of crankshaft rotation.

ii *6 t h Al 

1. In a rotary expansion engine capable of operating on a source of pressurized fluid externally located with respect to the engine, the combination comprising: a. a housing consisting of plural housing sections each of which define a cavity, the peripheral Surface of which are so formed as to define a plurality of lobes; b. a crankshaft supported for rotation in said housing; c. a multi-lobe rotor supported for eccentric rotation in each of said cavities and connected to rotate said crankshaft; d. each multi-lobe rotor having one more lobe than the number of housing lobes to define with its associated cavity a plurality of working chambers which successively expand and contract in volumetric size as the rotor rotates within its cavity; e. a source of pressurized fluid external of the housing of the rotary expansion engine; f. a plurality of intake and exhaust ports for each cavity circumferentially spaced from each other to provide a plurality of power impulses for every revolution of the associated rotor; g. the housing sections being angularly offset from each other and the rotors also being angularly offset from each other around the crankshaft so that the rotors and crankshaft are substantially dynamically balanced and the intake and exhaust ports of all the cavities are substantially angularly equispaced from each other around the crankshaft to effect thereby substantially equal spaced power impulses for every revolution of the rotors; h. each intake port being in communication with said source of pressurized fluid to receive and pass pressurized fluid into the working chambers; i. first valve means at each intake port to control flow of pressurized fluid therethrough; j. second valve means for controlling flow of spent pressurized fluid from each of the working chambers through the exhaust ports; and k. actuating means for moving said first valve means, in relation to rotation of the rotors in each of the cavities to open and closed positions.
 2. The apparatus of claim 1 wherein said actuating means is a gear train interconnecting each of the first valve means in synchronized relationship so that regardless of the position of the rotors at least one first valve means is open to admit pressurized fluid from said source thereof to effect rotation of the rotors in a preselected direction.
 3. The apparatus of claim 1 wherein there are two rotors disposed in two cavities and wherein each rotor is operatively connected to rotate one revolution for every three revolutions of the crankshaft.
 4. The apparatus of claim 1 wherein the engine has two rotors positionally indexed around the crankshaft from each other 180* and the housing sections positionally indexed about the crankshaft 90* from each other.
 5. The apparatus of claim 1 wherein the engine has two housing sections each of which defines a cavity having an epitrochoidal peripheral surface and wherein each rotor comprises a three lobe profile, the two rotors being positionally indexed about the longitudinal axis of the crankshaft 180* from each other and the housing sections together with their epitrochoidal peripheral surfaces being angularly offset 90* from each other about the longitudinal axis of the crankshaft.
 6. The apparatus of claim 1, wherein said source of pressurized fluid includes an intake manifold connected to communicate with each of said intake ports.
 7. The apparatus of claim 1 wherein each of said first valve means comprises a valve body disposed for rotation in a valve housing and wherein said valve housing has fluid flow passageway means for conducting cooling fluid.
 8. The apparatus of claim 1 wherein said housing has cooling fluid channels extending substantially parallel to the crankshaft axis and connected at one end to a source of cooling fluid to provide for a single pass of cooling fluid through the channels.
 9. The apparatus of claim 1 wherein each cavity has a basically epitrochoidal shape and each rotor has a three-lobe profile and wherein each cavity has a pair of intake and exhaust ports arranged to provide two power inpulses for each revolution of the crankshaft.
 10. The apparatus of claim 9 wherein said actUating means provides for opening a first valve means for every 180* of crankshaft rotation to permit flow of pressurized fluid through the associated intake port and into a working chamber.
 11. The apparatus of claim 9 wherein said actuating means provides for each power impulse the opening and closing of the associated first valve means within the period between about 90* to about 140* of crankshaft rotation and each exhaust port to open at about 270* of crankshaft rotation and close at about 495* of crankshaft rotation. 